CORE:  adding radioactivity file and settings

## Ready State: Yes

This pull request is related to the following JIRA tickets: https://imagex.atlassian.net/browse/LDC-236
Updates radioactivity settings with preference for medium activity radioactivity decay profile
updates radioactivity pointer from linux feature to imagex common_fields

## Requirements & Dependencies

* radioactivity

## Deployment Instructions

* Merge code.
## Usage/Test Instructions

ensure wiki CT enables with radioactivty field set to medium decay profile.